Semiconductor devices have been prepared in the past using various combinations of metallization over the circuit metal contact pads. Such combinations generally have included the use of thin films of refractory metals as well as gold and palladium, which require costly patterning steps involving hazardous material and chemical waste, and also generate stress in the semiconductor chips. They furthermore severely limit the choice of soldering materials for assembly and packaging. Although platinum, with titanium as undermetal, has been proposed in 1996 ("Self-Aligned, Fluxless Flip-Chip Bonding Technology for Photonic Devices", by J. F. Kuhmann, H. J. Hensel, D. Pech, P. Harde, and H.-G. Bach, Proc. 1996 Electronic Components and Technology Conference, May 1996), it was restricted to specialty III-V photonic devices and eutectic solder connections. For rerouting processes on semiconductor circuits, past technology offers only methods of questionable effectiveness to position the thin metal films across the sides or edges of the chip. In addition, the patterning processes for these thin metal films are expensive and generate liquid waste byproducts which must be disposed of. For forming cubes from a plurality of stacked chips, the known technology must rely on cumbersome, expensive methods. Known methods for assembling individual chips or finished cubes onto substrates often involve poorly compatible metallization and solders, with difficulty for aligning active parts and substrate.
In summary, the goal of offering for commercial and military systems cost-effective, reliable, rerouted semiconductor products, manufactured in high volume and with flexible, low-cost production methods, has remained elusive, until now.